pointers and functions

hello! i have this class called _button, it has x,y,w,h and a draw function. Now i need onclick function for it, i think it sould be pointer type variable, so i can apply something like this is main.cpp: button.onclick=&mycustomfunction. how do i do that and how do i define the variable?

you may want to look up polymorphism.

Hi,

Quote:

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Now i need onclick function for it, i think it sould be pointer type variable, so i can apply something like this is main.cpp: button.onclick=&mycustomfunction. how do i do that and how do i define the variable?

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Here is an example of using pointers to functions:

Code:

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#include <iostream>
using namespace std;

class MyButton
{
public:
       
        int x;
        int y;
        double (*onclick)(int a);

        MyButton()
        {
                x = 0;
                y = 0;
                onclick = 0;
        }

                 
};

double myCustomFunc(int a)
{
        cout<<a<<endl;
        return a + 2.0;
}


int main()
{
        MyButton b;
        b.onclick = myCustomFunc;

        double result = b.onclick(10);

        return 0;
}

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A pointer to a function must reflect the type of the function, and the type of a function includes the return type and the parameter types. You should note that myCustomFunc is not a member function of MyButton and therefore it does not have access to MyButton member variables unless they are public.